Genome-wide analysis of single nucleotide polymorphisms uncovers population structure in Northern Europe.
BACKGROUND
Genome-wide data provide a powerful tool for inferring patterns of genetic variation and structure of human populations.


RESULTS
In this study, we analysed almost 250,000 SNPs from a total of 945 samples from Eastern and Western Finland, Sweden, Northern Germany and Great Britain complemented with HapMap data. Small but statistically significant differences were observed between the European populations (F(ST) = 0.0040, p<10(-4)), also between Eastern and Western Finland (F(ST) = 0.0032, p<10(-3)). The latter indicated the existence of a relatively strong autosomal substructure within the country, similar to that observed earlier with smaller numbers of markers. The Germans and British were less differentiated than the Swedes, Western Finns and especially the Eastern Finns who also showed other signs of genetic drift. This is likely caused by the later founding of the northern populations, together with subsequent founder and bottleneck effects, and a smaller population size. Furthermore, our data suggest a small eastern contribution among the Finns, consistent with the historical and linguistic background of the population.


CONCLUSIONS
Our results warn against a priori assumptions of homogeneity among Finns and other seemingly isolated populations. Thus, in association studies in such populations, additional caution for population structure may be necessary. Our results illustrate that population history is often important for patterns of genetic variation, and that the analysis of hundreds of thousands of SNPs provides high resolution also for population genetics.
Salmela
Elina
E
Department of Medical Genetics, University of Helsinki, Helsinki, Finland.
Lappalainen
Tuuli
T
Fransson
Ingegerd
I
Andersen
Peter M
PM
Dahlman-Wright
Karin
K
Fiebig
Andreas
A
Sistonen
Pertti
P
Savontaus
Marja-Liisa
ML
Schreiber
Stefan
S
Kere
Juha
J
Lahermo
Päivi
P
D015331:Cohort Studies; D005060:Europe; D005387:Finland; D005787:Gene Frequency; D005819:Genetic Markers; D055106:Genome-Wide Association Study; D006801:Humans; D007802:Language; D008297:Male; D020641:Polymorphism, Single Nucleotide; D011153:Population / Q000235:genetics*
D005819:Genetic Markers